Maximum Possible Fuel Economy?

[killerFatty]

One thing I can add is that if the coolant temp sensor has never been replaced... DO IT! That has a major effect on MPGs.

By replacing mine my daily AVG went from 17-18mpg to 20-21mpg

IMHO this is the best mpg improver mentioned. When I got my car, I ran a tank of gas through it and was averaging 7 MPG. I almost cried. The first thing I did was this little sensor. My mpg went from 7 to 12 with a lead foot and about 15-16 under normal driving. Throttle response also improved significantly. I got my Coolent temp. sensor from autozone for $20 and its already saved twice that much in fuel.

Please fellas, lets not "Draft" behind 18 wheelers on the interstate. for one truckers really REALLY hate that, and big rigs are designed to stop quickly with a heavy load. if they have a reason to slam on the brakes, even your Bruce Lee reflexes will not save your LS transforming into an instant convertible, let alone take your head off. if you cant see the side mirrors of the big truck...back off or go around them.

I have talked to a more than a few big rig drivers that only use the trailer breaks and not the actuall truck breaks. That way they dont have to replace the breaks near as often. Having said this, I DON'T ADVOCATE DRAFTING!!! There is nothing worse than a *BLEEP*ed off trucker so dont do it.

[Marklouis]

One thing I can add is that if the coolant temp sensor has never been replaced... DO IT! That has a major effect on MPGs.

By replacing mine my daily AVG went from 17-18mpg to 20-21mpg

IMHO this is the best mpg improver mentioned. When I got my car, I ran a tank of gas through it and was averaging 7 MPG. I almost cried. The first thing I did was this little sensor. My mpg went from 7 to 12 with a lead foot and about 15-16 under normal driving. Throttle response also improved significantly. I got my Coolent temp. sensor from autozone for $20 and its already saved twice that much in fuel.

...Part # SU4007 from autozone. O.E.M.# 89422-20010

definately a worthwhile and easy replacement.

[curiousB]

Is there a procedure to test the sensor rather than just switching it out? Is it just a thermistor (resistor that varies with temperature)? If so can you just measure it with DVM and a thermometer and then lookup on some table what the resistor should be? Maybe have to do it at a couple of temp levels to be sure (fully warmed engine, cold engine).

[SRK]

Is there a procedure to test the sensor rather than just switching it out? Is it just a thermistor (resistor that varies with temperature)? If so can you just measure it with DVM and a thermometer and then lookup on some table what the resistor should be? Maybe have to do it at a couple of temp levels to be sure (fully warmed engine, cold engine).

Thanks for stating this. A failed ECU temp sensor will pop a code, and they are easily tested. Specs are provided to ensure that they are within range, but mostly when they fail, they fail completely and the engine goes into limp home mode.

As well, the fuel trims are established by the O2 sensors, so even if the sensor went out of range before failure, the O2's would maintain the fuel-air ratio.

Consequently the idea that changing the sensor as one would do for a spark plug is a good idea makes no sense to me. If it ain't broke, don't fix it.

[oldskewel]

Is there a procedure to test the sensor rather than just switching it out? Is it just a thermistor (resistor that varies with temperature)? If so can you just measure it with DVM and a thermometer and then lookup on some table what the resistor should be? Maybe have to do it at a couple of temp levels to be sure (fully warmed engine, cold engine).

Thanks for stating this. A failed ECU temp sensor will pop a code, and they are easily tested. Specs are provided to ensure that they are within range, but mostly when they fail, they fail completely and the engine goes into limp home mode.

As well, the fuel trims are established by the O2 sensors, so even if the sensor went out of range before failure, the O2's would maintain the fuel-air ratio.

Consequently the idea that changing the sensor as one would do for a spark plug is a good idea makes no sense to me. If it ain't broke, don't fix it.

To directly answer the testing question, yes there is a way. A pdf from the shop manual is listed halfway down the following page:

http://www.clublexus.com/forums/ls400-foru...-read-this.html

Not sure what year that is from, but it is on a different page from my '91 manual. But the thermistor plot is the same.

You basically take the thing out and measure resistance as you vary temperature across a range from freezing to boiling. Resistance should stay within a specified tolerance throughout the range. They show a picture with it in a pan of heated water as an example of how to do the test.

SRK sure knows what he's talking about, but it could be that there is an out-of-spec failure that would change the resistance, but not enough to fail completely. He has a good point that complete failure (e.g., open circuit) may be more likely than a significantly increased resistance. I don't know enough about these particular sensors to be sure.

However, to do the test, you basically have to take the thing out, and by that time, you almost may as well put a new one in. My plan - buy a new one, replace it, then test the old one as a science experiment with my kids. If good, I'll keep it as a spare.

[IS400]

You guys are really talking about apples and oranges unless you compare actual versions of the LS V-8. They vary widely in design over history of the car.

If you really want gas mileage, go to narrow tires. Rolling resistance is one of the biggest issues to tackly for fuel economy.

Prius, little tiny narrow tires. It is not just chance that it is designed that way.

I nearly fell asleep reading the OP, who must be just like Captain Slow on Top Gear UK.

[jcrome04]

Most of the time the coolant temp sensor just gets old and doesn't work as well as it used to.. most likely won't throw a code.. it's just something that should be replaced every once in a while.

It may not be broke enough to throw a code... but it IS "broke" enough to be hindering your fuel efficiency. My advice to anyone with a 1st or 2nd gen that has never had it replaced.. would be to change it out ASAP.

Your mileage/performance WILL improve!

[killerFatty]

Most of the time the coolant temp sensor just gets old and doesn't work as well as it used to.. most likely won't throw a code.. it's just something that should be replaced every once in a while.

It may not be broke enough to throw a code... but it IS "broke" enough to be hindering your fuel efficiency. My advice to anyone with a 1st or 2nd gen that has never had it replaced.. would be to change it out ASAP.

Your mileage/performance WILL improve!

I couldn't agree with you more!

[curiousB]

Guys this sensor change for the heck of it sounds like junk science. SRK stated that if they fail it tends to be a hard failure where the ECU detects it. To just change as if its a wear item like spark plugs, tires, or a timing belt seems unfounded. Has anyone replaced a temp sensor, where the ECU didn't "throw a code" and measured the sensor over temperature to see if it has drifted well off spec? Without doing that it seems little more than guessing. A thermistor is not a very complicated electronic component. How often have you changed the thermostat on your water heater, oven, or furnace?

I agree its not very expensive (someone said $20) but maybe a new air filter would be better for mileage than changing a sensor that may not be faulty.

[SRK]

Junk Science.....I like that term! That's exactly what this "sensor change" thing is....and when is the last time a temperature gauge sensor ( very similar ) gave spurious readings....more likely it just failed altogether, and on a Dodge, not a Lexus.

I smell an urban myth developing. CuriousB and I will squash it yet!

[Slvr99LS]

I believe there is validity to both sides regarding the sensor issue, but it may be unfair to term it 'junk science' just yet, as I have a theory. The one side of the coin is, "don't waste $$$ on frivolous parts that aren't bad." Fair enough. I believe most of us likely prefer saving money over intentionally wasting it. But, it's definitely worth mentioning 'Jcrome' certainly isn't the only long-term member of this forum who states he saw a substantial improvement in fuel economy and overal responsiveness by doing nothing other than changing out this mysterious coolant temperature sensor - there have been plenty of others. So let's not dismiss their findings so quickly. They have nothing monetarily or tangibly to gain by starting or perpetuating a myth, right? I'd say this forum is generally filled with helpful, good-intentioned people. But, that's not to say the topic doesn't warrant further thought and consideration.

My theory... and it's a fairly simple one involving thermal conductivity, goes a little something like this: Anyone who has ever viewed the inside of an older, well-used radiator has seen the tell-tale accumulation of crusty rust and scale deposits. Give it enough time, mileage, and particularly anti-freeze neglect (lack of periodic flushing and replenishment), and the entire cooling system obviously starts to suffer from an efficiency standpoint. The transfer of thermal energy from the hot coolant to the radiator is no longer anywhere near as effective. In extreme cases, the engine may even eventually overheat on a warm day with no clearly obvious cause.

Now... bear with me here. This particular sensor is living in a hostile environment, projected into the coolant flow at the intake manifold for the life of the engine. With suitable age and mileage, a similar insulative crust may form on it which could easily be giving false readings... and those readings would tend to be low, i.e. telling the ECU the engine has not reached full operating temperature, thereby providing a richer mixture at virtually all throttle settings. Voila - a significant loss of fuel economy, and no check engine light! The sensor could easily still test within accepted parameters. Again, I'm sure I'm opening the usual can of worms... and I'm prepared for the backlash that comes with a differing view, so let's be adults here. It's only a theory, but it seems in my pea-brain to hold water. No pun intended. And for the record, I just spent substantially more on an air filter than the mentioned cost of the aftermarket replacement version of this temp sensor. Could thoroughly cleaning the sensor rather than replacing it make a difference? Perhaps - I haven't noted where anyone has attempted it, since it's so inexpensive to replace. Anyone?

Over the years as a tech, I've had other engine control related sensors give problems without triggering codes and still measure well within stated tolerances. Perfect example is a GM TPS (throttle position sensor). Basically just a variable resistor sealed in a plastic case with a pair of conductive carbon tracks inside and a pair of metal 'fingers' which sweep as the throttle valve opens and closes. In a nutshell, it tells the computer where your foot is on the gas pedal. I've had several of these, on different cars, cause driveability problems without ever registering a code. Their voltage output to the ECU also fell within specs at both idle and WOT, but small virtually microscopic breaks or wear in the carbon tracks (particularly in the mid-range where most driving time is spent) were causing suitably inconsistent output from the sensor that it drives the ECU crazy. Swap out the sensor and the symptoms vanish like magic. And that's just one example. Simple facts: things do wear, none of us knows everything, and no technology is perfect. 'Nuff said for now.

Back to the temp sensor - beyond mine, any other theories out there other than to just dismiss the whole thing as wishful thinking? Not stating for a second that everyone should just go ahead and replace theirs, but I believe there is something to it.

[curiousB]

Just searching for the truth. Certainly no personal agenda here. A lot more people read these posts than chime in so we owe it to the entire community to be rigorous of ourselves.

I think the most compelling point is that some such as jcrome have only changed sensor and seen presumably immediate results to MPG. That assumes they did nothing else. No new “super slippery” oil, new tires, higher tire inflation, warmer drier days, or they took a mostly downhill trip from a mountaintop (I think jcrome can see the Cascades) ;) . If this is truly an A vs B test where all else was held constant then there is some merit here.

As for the coating of the sensor I don’t think this theory is terribly compelling. The insulation properties of a few microns of deposit wouldn’t change the thermal mass of the probe significantly. From a thermal modeling point of view the fact that the probe is inserted in a fluid that is circulated and represents a much larger thermal mass would mean the probe sees the true liquid temperature without any meaningful lag. In any event this isn’t a rapidly changing temperature environment (total thermal mass of engine block and coolant system is very large so won’t jump around too quickly) which makes temperature tracking easier. I’m quite sure the probe sees the liquid temperature. There may be a case that it’s resistance vs. temp curve changes over time but this is only conjecture.

I don’t know how the ECU factors engine temp into its computations. I would suspect O2, throttle position, RPMs, air temp, and air mass sensors are far more important inputs to the fuel air algorithms in the ECU. In general I think the ECUs try to minimize the gas metered to the engine as long as the RPMs are maintained at a given throttle position. Perhaps the sensor comes into importance at start up to send a richer mixture and higher idle speed until warmed up but this would be immaterial in a tank full of gas MPG test.

The GM throttle position sensor is also not a perfect example. Such a wear problem is common for position sensors as they have moving components. The only way to avoid this wear is to go to all optical sensors and they generally cost more. So position sensors based on potentiometers (variable resistor) are indeed wear items (I had to change my LS430 rear axle ride height sensor for this reason). I think a little more effort by GM in their ECU software and they could trap an error for erratic readings but they must not see the cost benefit of the additional software being worth it. In the old days radios used potentiometers for the volume controls (it’s all electronic now). Ever recall turning the volume and hearing a crackling noise in the speaker? This is a dirty or worn out potentiometer.

I think the only way to either validate or disprove the temp sensor is to measure one that was taken out. See if it still a sound resistor (i.e. didn’t fail into a short or open circuit) and then check a few values at different temps to see if it has drifted off the R vs T curve designed for it.

This is why I asked if there was a procedure, much like throwing the “old thermostat on the stove in boiling water with a thermometer” test. That way you can have some certainty that the part you are buying is going to fix something. I looked at www.parts.com and see there sensors are closer to $50 and once you add in shipping maybe $55-60. So to me I think I’d run a quick test on the stove.

[oldskewel]

... With suitable age and mileage, a similar insulative crust may form on it which could easily be giving false readings... and those readings would tend to be low, i.e. telling the ECU the engine has not reached full operating temperature, thereby providing a richer mixture at virtually all throttle settings. Voila - a significant loss of fuel economy, and no check engine light! ...

I replaced mine yesterday in my '91. Followed some of the instructions in the shop manual, but in case anyone else tries, they tell you to remove a few things you don't need to touch. It took a while to get to it. When removed, it measured ~2k Ohms, which is ~right on spec for room temp.

There was no crust or scale at all on it. Slight, almost oily film on it that wiped off with a paper towel. Nothing that would impede heat transfer.

Old part in hand, I then went to Kragen and got a replacement (non-OEM for $13.99) that looked like a perfect match and also measured ~2k Ohms at room temp. I put the new part in.

Sorry to foul up the scientific value of this test, but with the throttle body exposed after removing all those other parts, I could not resist cleaning it. Toothbrush on a stick, spraying in solvent, paper towels, etc. got a lot of black stuff out of there.

As far as I can tell (I'm 2nd owner, but have all records from previous owner) this is the first time the TB was cleaned and the temp sensor was replaced.

The car sure felt lively on a quick test drive, but nothing I can quantify yet. I log my gas mileage, so I'll see if it improves over the next tank or so. I'll also do a test over the full temperature range of the part I removed to see if anything is out of spec.

So

- it seems like I removed and replaced a perfectly good part

- car feels more responsive (purely subjective, maybe because I'm a believer)

- I also cleaned the TB, meaning if performance improved, I won't know which change did it.

[jcrome04]

I wasn't throwing a code, conditions were the same (as I did this a couple months ago before the warm weather started), no new "slippery" oil, and my avg. MPG went from 17-18 to 20-21... That's a pretty good increase for just changing one sensor.

Do some searching, SKPerformance had a huge thread about this topic recently too. As far as I know EVERYONE I've talked to who has changed out the Coolant Temp Sensor has NOT had a CEL, or CEL related, and have all had very positive results.

http://www.clublexus.com/forums/ls400-foru...l-in-1-fix.html

Just because it's not broken enough to throw a code.. doesn't mean it's 100%

Just like an O2 sensor that isn't broken enough to throw a sensor code, but IS broken enough to throw a bad cat code.

Sensors can stop working "as good as new". My ECT Sensor had never been changed. That would be an ~13 year old sensor... maybe... juat MAYBE... it wasn't working as efficiently as it was 13 years ago...

And Oldskewel I am eager to hear your results. Cleaning the throttle body is usually just a smoothness and performance increase, not really MPG, so if you DO experience +MPGs I'd opt to attribute it to the coolant temp sensor.

[oldskewel]

... With suitable age and mileage, a similar insulative crust may form on it which could easily be giving false readings... and those readings would tend to be low, i.e. telling the ECU the engine has not reached full operating temperature, thereby providing a richer mixture at virtually all throttle settings. Voila - a significant loss of fuel economy, and no check engine light! ...

I replaced mine yesterday in my '91. Followed some of the instructions in the shop manual, but in case anyone else tries, they tell you to remove a few things you don't need to touch. It took a while to get to it. When removed, it measured ~2k Ohms, which is ~right on spec for room temp.

There was no crust or scale at all on it. Slight, almost oily film on it that wiped off with a paper towel. Nothing that would impede heat transfer.

Old part in hand, I then went to Kragen and got a replacement (non-OEM for $13.99) that looked like a perfect match and also measured ~2k Ohms at room temp. I put the new part in.

Sorry to foul up the scientific value of this test, but with the throttle body exposed after removing all those other parts, I could not resist cleaning it. Toothbrush on a stick, spraying in solvent, paper towels, etc. got a lot of black stuff out of there.

As far as I can tell (I'm 2nd owner, but have all records from previous owner) this is the first time the TB was cleaned and the temp sensor was replaced.

The car sure felt lively on a quick test drive, but nothing I can quantify yet. I log my gas mileage, so I'll see if it improves over the next tank or so. I'll also do a test over the full temperature range of the part I removed to see if anything is out of spec.

So

- it seems like I removed and replaced a perfectly good part

- car feels more responsive (purely subjective, maybe because I'm a believer)

- I also cleaned the TB, meaning if performance improved, I won't know which change did it.

I just measured (on the old, original, 18 years and 160k+ miles part) resistance of 240 Ohms at 100*C (boiling water). From the '91 manual, page FI-68, the spec range for this temp is ~120-250 Ohms. So it is within spec, although at the high end of it. At room temp, ~2000 Ohms measured, spec range is ~1700-2800 (the ~ in the specs is because I'm reading off a log-scale plot).

So this looks like I replaced a good part. No regrets though.

Also, no CEL's ever (I've actually never ever seen one on this car - I guess that's what I get for staying ahead of things).

[jcrome04]

Just keep an eye on your MPGs.

SKPs thread here on LOC..

http://us.lexusownersclub.com/forums/index...c=56145&hl=

[Slvr99LS]

Just searching for the truth. Certainly no personal agenda here. A lot more people read these posts than chime in so we owe it to the entire community to be rigorous of ourselves.

I think the most compelling point is that some such as jcrome have only changed sensor and seen presumably immediate results to MPG. That assumes they did nothing else. No new “super slippery” oil, new tires, higher tire inflation, warmer drier days, or they took a mostly downhill trip from a mountaintop (I think jcrome can see the Cascades) ;) . If this is truly an A vs B test where all else was held constant then there is some merit here.

As for the coating of the sensor I don’t think this theory is terribly compelling. The insulation properties of a few microns of deposit wouldn’t change the thermal mass of the probe significantly. From a thermal modeling point of view the fact that the probe is inserted in a fluid that is circulated and represents a much larger thermal mass would mean the probe sees the true liquid temperature without any meaningful lag. In any event this isn’t a rapidly changing temperature environment (total thermal mass of engine block and coolant system is very large so won’t jump around too quickly) which makes temperature tracking easier. I’m quite sure the probe sees the liquid temperature. There may be a case that it’s resistance vs. temp curve changes over time but this is only conjecture.

I don’t know how the ECU factors engine temp into its computations. I would suspect O2, throttle position, RPMs, air temp, and air mass sensors are far more important inputs to the fuel air algorithms in the ECU. In general I think the ECUs try to minimize the gas metered to the engine as long as the RPMs are maintained at a given throttle position. Perhaps the sensor comes into importance at start up to send a richer mixture and higher idle speed until warmed up but this would be immaterial in a tank full of gas MPG test.

The GM throttle position sensor is also not a perfect example. Such a wear problem is common for position sensors as they have moving components. The only way to avoid this wear is to go to all optical sensors and they generally cost more. So position sensors based on potentiometers (variable resistor) are indeed wear items (I had to change my LS430 rear axle ride height sensor for this reason). I think a little more effort by GM in their ECU software and they could trap an error for erratic readings but they must not see the cost benefit of the additional software being worth it. In the old days radios used potentiometers for the volume controls (it’s all electronic now). Ever recall turning the volume and hearing a crackling noise in the speaker? This is a dirty or worn out potentiometer.

I think the only way to either validate or disprove the temp sensor is to measure one that was taken out. See if it still a sound resistor (i.e. didn’t fail into a short or open circuit) and then check a few values at different temps to see if it has drifted off the R vs T curve designed for it.

This is why I asked if there was a procedure, much like throwing the “old thermostat on the stove in boiling water with a thermometer” test. That way you can have some certainty that the part you are buying is going to fix something. I looked at www.parts.com and see there sensors are closer to $50 and once you add in shipping maybe $55-60. So to me I think I’d run a quick test on the stove.

Actually Curious, the GM throttle position sensor IS a perfect example... a perfect example of the point I was trying to make - that all is not always as it seems, a component can experience a partial failure, and not every sensor related issue will throw a code. Are we in agreement on at least those points? You're also understating how significant the temp sensor input is to the overall fuel curve. In many of our racing vehicles (most are still street-driven as well), a low-temperature thermostat is almost always installed (generally 160F). Factory 195-degree thermostats aren't even fully open in most cases until 210-215... heck, some vehicles don't even turn on the secondary electric cooling fan until temps reach more than 230 degrees fahrenheit! Not exactly conducive to making consistent power. Sure does thin out an oil too. We won't even get into the other detrimental effects of high coolant temperatures on an engine over long periods of time. Legions of gasket failures are but one byproduct. But for drag racing, the heat-soak between rounds is so significant, it's been proven to be worthwhile to pack the intake down thoroughly with ice. We're after cool air there... cool air = denser air, which means more fuel can be added and greater power output experienced for a given set of conditions. The lower coolant temps also signal the ECU to deliver a slightly richer mixture, and not just at WOT throttle settings. A very simplified model of how things react in the real world, but for this discussion, it works. We won't get into adiabatic engine theory here, as that's a topic for a potentially whole new thread. Suffice it to say, factory engineers are after very low emissions, and maximized fuel economy (meet CAFE standards - easier said than done). They also have to walk the fine line between longevity, power output, and the aforementioned emissions and fuel economy. Not an easy job.

Sorry you don't find my theory particularly compelling, but I haven't heard anyone provide a better one yet. When one is given that presents a valid scenario, I'll give it the strongest of consideration. I recognize your desire to discount the observations I've presented, but we're also potentially talking about a whole lot more than "a few microns" worth of deposits here. I've seen rust/scale/corrosion more than an 1/8-inch thick in older cooling systems. I've also seen complete system failure. Basically plugged solid. Stuff turns to mud for lack of a better term. Ever seen what some supposedy 'extended-life' coolants like DexCool can do to a cooling system? There's been pending class-action litigation out there on this very topic for years. Try Googling "dexcool failures" and prepare for a full nights worth of reading.

Having been around the block more than a few times... I stand by my assertions. Perhaps your maintenance regimen is superior to that of many others. I did note you own a much newer model of LS, so it's pretty clear your 2004 model is unlikely to suffer many of the maladies of an 18 year old vehicle for example. The majority of owners who've experienced dramatic improvements by replacing the coolant temp sensor are those with first or second-gen cars. Most have well over 100,000 miles. Many have 200,000 on the clock.... some, 300K. Probably safe to say most are riding around with the original, factory installed sensor still onboard. As previously stated.... I continue to believe there is something to it.

[curiousB]

that all is not always as it seems, a component can experience a partial failure, and not every sensor related issue will throw a code. Are we in agreement on at least those points?

To me comparing an electromechanical component to a passive electrical component is a very big canyon to cross. One moves and has wear elements the other just sits there and conducts electricity. Both are subject to potential failure but the electromechanical one is probably >1000x more likely to fail. So that is the basis for discounting the comparison.

Let’s just agree to disagree on the sensor coating theory. My case wouldn’t change much if it had 1/8” of gunk on it. All that an insulating coating will do is delay the time it takes the sensor to get to the proper reading. Given the sensor is immersed in a liquid (rather than air) that makes a major difference to the thermal transfer. The thermal mass of the engine block and coolant pool as I said before is a huge heat sink that resists rapid temperature changes. As a result a little time lag on the sensor won’t matter. The only important job for the coolant sensor is to return a resistive value for a given temperature and do this with repeatability (i.e. the same value for the same temp each time).

A failed coolant sensor fails to an open circuit. This is how resistors generally fail in circuits. Active devices like transistors on the other hand fail to a short circuit as the junction welds itself together upon failure. So a failed coolant sensor will be an open circuit and will be easily detected by the ECU. The possibility of an intermittent failure is there but it is more likely a corroded connector than the sensor element per say. Either way an intermittent will be an open and the ECU should detect that as well. The only other possibility is if the sensor resistance vs. temperature curve “ages” over time. I don’t believe this is true due to the composition of these devices but this is why I suggest we measure units replaced. Oldskewl just measured his and he concluded it is still working.

Just trying to get to the truth so people don’t start popping in new coolant sensors like they were changing an oil filter. I just don’t see them as a wear item. A potential failing item (and ECU detectable) but not wear.

[Marklouis]

..so THAT'S what a converasation between two intellectuals look like B)

both curiosB and slvr99LS have good points and seem well experienced in the tech/mech/elect. fields, and im sure both have learned some of thier knowledge through trial and error, which has been my knowledge base for most of my life, and I will on occasion follow the advice of someone who i feel has been around the block a few times more than me, sometimes mislead, sometimes right on target. i will give anyone the benefit of the doubt if they are off 1% of the time, thier experience with a repair or replacement may be a different result from everyone elses - his results are different based on the set of circumstances that has taken place - that doesnt mean that he is off base at all.

...so if i experience the same result on my repair im going to assume this is a sure thing - cause im a trial and error kind of guy and its just a 2 step proccess. if my results are different and no change at all, im still on the plus side because im only out $20, did some 1 on 1 wrench time with the Lexus - always a good thing - and I have 1 more new part in my ride. now if it was a $500 part my tune may be different, but i dont see any harm in this repair. ;)

besides, we got off base from the OP! :P

[SRK]

I am always amazed by how conjecture, opinion, anecdotal evidence, self-fulfilling prophecy, blind adherence, rationalization, and dogma can be passed off as science. Of course many people believe there is a grey-bearded guy who lives in the sky.

Change your sensors, avoid the Bermuda Triangle, practice safe hiking around sasquatch, and consult the stars for your future. Myself, I trust science.

Submitted respectfully,

SRK.

[IS400]

"To measure the true worth of an intellectual, ask them how they feel about astrology."

"One person's magic is another's engineering."

"What are the facts and to how many decimal points, all else is nonsense."

-- R. Heinlein, 1968.

[Marklouis]

I am always amazed by how conjecture, opinion, anecdotal evidence, self-fulfilling prophecy, blind adherence, rationalization, and dogma can be passed off as science. Of course many people believe there is a grey-bearded guy who lives in the sky.

Change your sensors, avoid the Bermuda Triangle, practice safe hiking around sasquatch, and consult the stars for your future. Myself, I trust science.

Submitted respectfully,

SRK.

lol! That's good! All that you mentioned are created from the Human psyche-and they have to co-exist with each other, because they all have flaws - even science. The atom was once thought as the smallest particle, now its suggested string theory is the base of matter. Lamonin, and telemores are marvelous discoveries, (google when you have a chanceY

Even Einstein believed in a intelligent creator - I would have a grey beard too if I had to deal with the human race.

its good you have faith in science, I do as well and hope to learn as much as you guys. Your technical knowledge is off the scale! but please don't put down others opinions as if somehow they are beneath your own.

Also respectfully.

[jcrome04]

I still recommend to replace the sensor. It's cheap and yields actual results. Everyone I've talked to on these forums and on CL that has replaced this part has experienced positive results.

I spent $50 on a sensor.. and gained 3mpg and now can get +30mpg highway... It pays itself off.

Awesome debate. That's what I like to see here B) So.. _{(other than ECT Sensor...)} How can we improve MPGs?

[curiousB]

How can we improve MPGs?

I think Obama was quoted as saying Americans need to check their tire inflation. How about a tire gauge to every taxpayer in the country?

[Slvr99LS]

Hey J, I'll be getting back to the intent behind the original post shortly and proceeding with my mileage tests, followed by the results. I've had my hands completely full with this car over the course of the last month (much of it documented here on the forums in the hope someone could benefit from the experiences), so much so that it's single-handedly diverted my attention from other projects which are always on the burner.

Anyhow, you're probably correct - 35MPG is definitely asking a lot from the car, but that was the intent. I've spent most of my life pushing the boundaries, and this is no exception... though it's definitely less likely to cause serious injury. :D Regardless of whether it achieves the 'magic number', it's worth the attempt in my opinion. The lessons learned from it should be applicable to any year/make/model of vehicle. I've never previously attempted anything like this, nor did I care to. I'm a motorsports nut who really never gave fuel economy much thought... what a boring topic, at least on the surface. Then you start to dig into the engineering aspects and psychology behind it... and... it's intriguing. Guess one could say I had an epiphany of sorts. This past year or two has seemingly been a really pivotal point in our global economy. I took it as a wake-up call that did more than vaporize the 401K. Not trying to divert the thread with a political statement, but watch the cost of a barrel of oil soar through that $100 mark again (taking the price of gasoline right along with it) and you'll see a huge jump in national interest again in this sort of efficiency-related experimentation. So why wait? Be ahead of the curve. Definitely isn't any harm in it other than the road-rage it might instill in others on the freeway because you're actually doing close to the speed limit. Need a bright flashing neon sign that says: "just testing" to avoid being rear-ended at 70 by the lady in the Dodge Caravan who's late for Jimmy's soccer practice. B)

So far the mileage with this LS has already picked up dramatically from just fluid and filter changes, along with moderately increasing the air pressure in the tires. The results were so encouraging that it led me to write the OP. I definitely never expected the level of feedback from this thread that it has received, and I appreciate everyones time and thought-provoking insights. Awesome to hear that your car has gotten 30+mpg already. That's really encouraging. More to come....

P.S. I've also decided against any type of 'hypermiling' attempt at the moment... seems that's more of a test of a drivers skill and use of various controversial techniques than a realistic display of a vehicles mileage capabilities in 'real-world', everyday driving. I can see where it could get addictive though and take over your life - "I got 49mpg out of my diesel Jetta... I just KNOW I can get 50~!!"